Multi-positional camshaft phaser with switchable one-way wedge clutches

ABSTRACT

A camshaft phaser including a rotatable stator arranged to receive torque from an engine, a hub arranged to non-rotatably connect to a camshaft and including first and second pluralities of circumferentially disposed ramps, a first wedge plate including: a first aperture and a third plurality of circumferentially disposed ramps engaged with the first plurality of circumferentially disposed ramps, a second wedge plate including: a second aperture and a fourth plurality of circumferentially disposed ramps engaged with the second plurality of circumferentially disposed ramps, and an engagement assembly including a shaft extending axially through the first and second apertures. For an advance or retard mode, the shaft is arranged to be displaced axially so that the hub is rotatable with respect to the stator in a first or second circumferential direction.

TECHNICAL FIELD

The present disclosure relates to a multi-positional camshaft phaser with two one-way wedge clutches. In particular, the two one-way wedge clutches are used to transmit torque from a stator to a camshaft and to advance and retard the phase of the camshaft with respect to the stator using oscillating torsional forces transmitted to the phaser by the camshaft.

BACKGROUND

Variable camshaft timing (VCT) devices are known in the art to improve engine performance in terms of fuel economy, reduced emissions and/or increased torque by changing the positional relationship of camshafts to vary the timing of the engine in terms of operation of intake valves relative to its exhaust valves or in terms of the operation of its valves relative to the position of the crankshaft.

U.S. Pat. No. 9,080,471 (BorgWarner, Inc.) describes a cam torque actuated phaser with mid position lock. However, the phaser relies on a relatively complicated hydraulic scheme to implement the phasing. Additionally, the phaser is not multi-positional.

SUMMARY

According to aspects illustrated herein, there is provided a camshaft phaser including a rotatable stator arranged to receive torque from an engine, a hub arranged to non-rotatably connect to a camshaft and including first and second pluralities of circumferentially disposed ramps, a first wedge plate including: a first aperture and a third plurality of circumferentially disposed ramps engaged with the first plurality of circumferentially disposed ramps, a second wedge plate including: a second aperture and a fourth plurality of circumferentially disposed ramps engaged with the second plurality of circumferentially disposed ramps, and an engagement assembly including a shaft extending axially through the first and second apertures. For an advance mode, the shaft is arranged to be displaced in a first axial direction so that the hub is rotatable with respect to the stator in a first circumferential direction. For a retard mode, the shaft is arranged to be displaced in a second axial direction, opposite the first axial direction, so that the hub is rotatable with respect to the stator in a second circumferential direction, opposite the first circumferential direction.

According to aspects illustrated herein, there is provided a camshaft phaser including a rotatable stator arranged to receive torque from an engine, a hub arranged to non-rotatably connect to a camshaft and including first and second pluralities of circumferentially disposed ramps, a first wedge plate including: a first plurality of apertures and a third plurality of circumferentially disposed ramps engaged with the first plurality of circumferentially disposed ramps, a second wedge plate including: a second plurality of apertures and a fourth plurality of circumferentially disposed ramps engaged with the second plurality of circumferentially disposed ramps, and an engagement assembly including a plurality of shafts extending axially through the first and second pluralities of apertures. For a drive mode, the first and second wedge plates are arranged to be rotatable with respect to the plurality of shafts so that the first and second wedge plates rotate with respect to the hub and non-rotatably connect to the rotatable stator and the hub. To initiate an advance mode, the second wedge plate is arranged to be rotatable with respect to the plurality of shafts so that the second wedge plate rotates with respect to the hub and non-rotatably connects to the rotatable stator and the hub. To initiate a retard mode, the first wedge plate is arranged to be rotatable with respect to the plurality of shafts so that the first wedge plate rotates with respect to the hub and non-rotatably connects to the rotatable stator and the hub.

According to aspects illustrated herein, there is provided a method of phasing a camshaft, including the steps of receiving, using a rotatable stator non-rotatably connected to a housing, torque from an engine; for an advance mode, displacing a shaft for an engagement assembly, the shaft extending axially through first and second apertures in first and second wedge plates, respectively, in a first axial direction so that: a first plurality of circumferentially disposed ramps for a hub, arranged to non-rotatably connect to a camshaft, engage a second plurality of circumferentially disposed ramps for the first wedge plate to block rotation of the hub, with respect to the stator in a first circumferential direction, and the hub is rotatable with respect to the stator in a second circumferential direction, opposite the first circumferential direction; for a retard mode, displacing the shaft for the engagement assembly in a second axial direction, opposite the first axial direction so that: a third plurality of circumferentially disposed ramps for the hub engage a fourth plurality of circumferentially disposed ramps for the second wedge plate to block rotation of the hub, with respect to the stator in the second circumferential direction, and the hub is rotatable with respect to the stator in the first circumferential direction; and, for a drive mode, displacing the shaft for the engagement assembly in the first or second axial direction to block rotation of the hub, with respect to the stator in the first and second circumferential directions.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are disclosed, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, in which:

FIG. 1 is a perspective view of a cylindrical coordinate system demonstrating spatial terminology used in the present application;

FIG. 2A is a schematic front elevational view of a camshaft phaser with two one-way wedge clutches and an engagement shaft assembly omitted;

FIG. 2B is a schematic rear elevational view of the camshaft phaser in FIG. 2A;

FIG. 3 is a schematic perspective exploded view of the camshaft phaser in FIG. 2A including the engagement shaft assembly;

FIG. 4 is a schematic front elevational view of a hub of the camshaft phaser in FIG. 2A;

FIG. 5 is a schematic rear elevational view of the hub of the camshaft phaser in FIG. 2A;

FIG. 6A is a schematic front elevational view of a first one-way wedge plate of the camshaft phaser in FIG. 2A;

FIG. 6B is a schematic rear elevational view of a second one-way wedge plate of the camshaft phaser in FIG. 2A;

FIG. 7A is a schematic partial cross-sectional view taken generally along line 7-7 in FIG. 2A with the engagement shaft assembly in an advance mode;

FIG. 7B is a schematic partial cross-sectional view taken generally along line 7-7 in FIG. 2A with the engagement shaft assembly in a drive mode;

FIG. 7C is a schematic partial cross-sectional view taken generally along line 7-7 in FIG. 2A with the engagement shaft assembly in a retard mode; and,

FIG. 8 is a schematic front elevational view of the stator for the camshaft phaser in FIGS. 2A and 2B.

DETAILED DESCRIPTION

At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the disclosure. It is to be understood that the disclosure as claimed is not limited to the disclosed aspects.

Furthermore, it is understood that this disclosure is not limited to the particular methodology, materials and modifications described and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present disclosure.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. It should be understood that any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure. It should be appreciated that the term “substantially” is synonymous with terms such as “nearly”, “very nearly”, “about”, “approximately”, “around”, “bordering on”, “close to”, “essentially”, “in the neighborhood of”, “in the vicinity of”, etc., and such terms may be used interchangeably as appearing in the specification and claims. It should be appreciated that the term “proximate” is synonymous with terms such as “nearby”, “close”, “adjacent”, “neighboring”, “immediate”, “adjoining”, etc., and such terms may be used interchangeably as appearing in the specification and claims. By “non-rotatably connected” components, we mean that the two components are connected so that whenever one of the components rotates the other component rotates and vice versa.

FIG. 1 is a perspective view of cylindrical coordinate system 10 demonstrating spatial terminology used in the present application. The present application is at least partially described within the context of a cylindrical coordinate system. System 10 includes longitudinal axis 11, used as the reference for the directional and spatial terms that follow. Axial direction AD is parallel to axis 11. Radial direction RD is orthogonal to axis 11. Circumferential direction CD is defined by an endpoint of radius R (orthogonal to axis 11) rotated about axis 11.

To clarify the spatial terminology, objects 12, 13, and 14 are used. An axial surface, such as surface 15 of object 12, is formed by a plane parallel to axis 11. Axis 11 is coplanar with planar surface 15; however it is not necessary for an axial surface to be coplanar with axis 11. A radial surface, such as surface 16 of object 13, is formed by a plane orthogonal to axis 11 and coplanar with a radius, for example, radius 17. Surface 18 of object 14 forms a circumferential, or cylindrical, surface. For example, circumference 19 forms a circle on surface 18. As a further example, axial movement is parallel to axis 11, radial movement is orthogonal to axis 11, and circumferential movement is parallel to circumference 19. Rotational movement is with respect to axis 11. The adverbs “axially,” “radially,” and “circumferentially” refer to orientations parallel to axis 11, radius 17, and circumference 19, respectively.

FIG. 2A is a schematic front elevational view of camshaft phaser 100 with one-way wedge clutches 106 and 108 and engagement shaft assembly 142 omitted.

FIG. 2B is a schematic rear elevational view of camshaft phaser 100 in FIG. 2A.

FIG. 3 is a schematic perspective exploded view of camshaft phaser 100 in FIG. 2A including engagement shaft assembly 142.

FIG. 4 is a schematic front elevational view of hub 104 of camshaft phaser 100 in FIG. 2A.

FIG. 5 is a schematic rear elevational view of hub 104 of camshaft phaser 100 in FIG. 2A.

FIG. 6A is a schematic front elevational view of one-way wedge plate 106 of camshaft phaser 100 in FIG. 2A.

FIG. 6B is a schematic rear elevational view of one-way wedge plate 108 of camshaft phaser 100 in FIG. 2A. The following should be viewed in light of FIGS. 2 through 6B. Camshaft phaser 100 includes rotatable stator 102 arranged to receive torque from an engine (not shown), hub 104, wedge plate 106, wedge plate 108, and engagement shaft assembly 142. Camshaft phaser 100 is rotatable about axis of rotation AR. Stator 102 is rotatable in circumferential directions CD1 and CD2. Hub 104 is arranged to non-rotatably connect to a camshaft (discussed further below) and includes circumferentially disposed ramps 114 and 116. Wedge plate 106 includes: at least one aperture A1 and circumferentially disposed ramps 126 engaged with circumferentially disposed ramps 114. Wedge plate 108 includes: at least one aperture B1 and circumferentially disposed ramps 128 engaged with circumferentially disposed ramps 116. Engagement assembly 142 includes shaft S1 extending axially through apertures A1 and B1.

FIG. 7A is a schematic partial cross-sectional view taken generally along line 7-7 in FIG. 2A with engagement shaft assembly 142 in an advance mode. Camshaft phaser 100 is arranged to non-rotatably connect to camshaft CS. Shaft S1 is arranged to be displaced in axial direction AD1 so that wedge plate 106 is non-rotatably connected to shaft S1. Hub 104 is rotatable with respect to stator 102 in circumferential direction CD1 and non-rotatable with respect to stator 102 in circumferential direction CD2. Rotation of hub 104, with respect to rotatable stator 102, in circumferential direction CD2 is blocked by wedge plate 108, which is rotatable with respect to shaft St Rotation of hub 104 in the advance mode is further described below.

FIG. 7B is a schematic partial cross-sectional view taken generally along line 7-7 in FIG. 2A with engagement shaft assembly 142 in a drive mode. For the advance mode, shaft S1 is arranged to be displaced in axial direction AD2, opposite axial direction AD1, so that hub 104 is substantially non-rotatably connected to stator 102 in circumferential directions CD1 and CD2. This connection is further described below. Neither wedge plate 106 nor wedge plate 108 is non-rotatably connected to shaft St In other words, wedge plates 106 and 108 are both rotatable with respect to shaft St As further described below, in the drive mode, wedge plates 106 and 108 are free to expand radially and contract radially so that wedge plates 106 and 108 engage ramps 114 and 116 of hub 104, respectively. Rotation of hub 104 in the drive mode is further described below.

FIG. 7C is a schematic partial cross-sectional view taken generally along line 7-7 in FIG. 2A with engagement shaft assembly 142 in a retard mode. For the retard mode, shaft S1 is arranged to be displaced in axial direction AD2 so that wedge plate 108 is rotatable with respect to stator 102. Hub 104 is rotatable with respect to stator 102 in circumferential direction CD2 and non-rotatable with respect to stator 102 in circumferential direction CD1. Rotation of hub 104, with respect to rotatable stator 102, in circumferential direction CD1 is blocked by wedge plate 106 which is rotatable with respect to shaft S1. Rotation of hub 104 in the retard mode is further described below.

FIG. 8 is a schematic front elevational view of stator 102 of camshaft phaser 100 in FIG. 2A. The following should be viewed in light of FIGS. 2 through 8. In an example embodiment, stator 102 includes at least one radially inwardly extending protrusion 174 disposed circumferentially between adjacent shafts S1, S2, S3, S4 and S5. Protrusion(s) 176 are configured to contact shaft(s) S1, S2, S3, S4 and S5 to limit a degree to which the rotational position of hub 104 can be shifted with respect to stator 102.

Ramps 114 are separated from ramps 116 in axial direction AD1. In an example embodiment (not shown), hub 104 can be formed of two hubs splined together where each respective hub includes circumferentially disposed ramps 114 and 116, respectively. In an example embodiment, rotatable stator 102 can be split into separate components. Wedge plates 106 and 108 are frictionally engaged with stator 102 and rotate with hub 104 except as noted below.

In an example embodiment, stator 102 includes a radially inner surface with circumferentially extending grooves 138 and 140. Radially outermost portion 106A of wedge plate 106 is at least partially disposed in circumferentially extending groove 138 and frictionally engaged with circumferentially extending groove 138. Radially outermost portion 108A of wedge plate 108 is at least partially disposed in circumferentially extending groove 140 and frictionally engaged with circumferentially extending groove 140. Due to the frictional engagement between wedge plates 106 and 108 and circumferentially extending grooves 138 and 140, respectively, wedge plates 106 and 108 rotate with stator 102 except as noted.

Radially outermost surface 118 of ramps 114 extend further in radially outer direction RD1 along circumferential direction CD2. That is, radial distance 120 increases along direction CD2. Radially outermost surface 122 of ramps 116 extend further in radially outer direction RD1 along circumferential direction CD1. That is, radial distance 124 increases along direction CD1.

Radially innermost surface 130 of ramps 126 extend further in radially inner direction RD2 along circumferential direction CD1. That is, radial distance 132 decreases along direction CD1. Radially innermost surface 134 of ramps 128 extend further in direction RD2 along circumferential direction CD2. That is, radial distance 136 decreases along direction CD2.

Shaft S1 includes portion P1 having outer diameter OD1, portion P2 having outer diameter OD2 and portion P3 having outer diameter OD3 greater than outer diameters OD1 and OD2. Portion P3 is arranged axially between portions P1 and P2. In an example embodiment, diameters OD1 and OD2 are equal.

In the advance mode, portion P3 is disposed in aperture A1 and portion P2 is disposed in aperture B1. In the retard mode, portion P3 is disposed in aperture B1 and portion P1 is disposed in aperture A1. In the drive mode, portion P1 is disposed in aperture A1, portion P2 is disposed in aperture B1, and apertures A1 and B1 are arranged to rotate with respect to shaft S1 to enable relative rotation between wedge plates 106 and 108, respectively, and hub 104. In the drive mode, portion P3 is not disposed in either apertures A1 or B1.

To shift from the drive mode to the advance mode, shaft S1 is arranged to block rotation of wedge plate 106 with respect to hub 104 and aperture B1 is arranged to rotate with respect to shaft S1 to enable relative rotation between wedge plate 108 and hub 104. That is, wedge plate 108 is arranged to rotate with respect to shaft S1 to enable relative rotation between wedge plate 108 and hub 104. To shift from the drive mode to a retard mode, shaft S1 is arranged to block rotation of wedge plate 108 with respect to hub 104 and aperture A1 is arranged to rotate with respect to shaft S1 to enable relative rotation between wedge plate 106 and hub 104. To shift from the drive mode to the advance mode, aperture B1 is arranged to rotate, with respect to shaft S1, in circumferential direction CD1. To shift from the drive mode to the retard mode, aperture A1 is arranged to rotate, with respect to shaft S1, in circumferential direction CD2.

Engagement assembly 142 includes plate 146 directly connected to axial end E1 of shaft S1 and plate 148 directly connected to axial end E2, opposite axial end E1, of shaft S1. In an example embodiment, engagement assembly 142 includes actuator 150 arranged to displace plate 146 in axial direction AD2 and actuator 151 arranged to displace plate 148 in axial direction AD1. Plate 148 is coupled to shaft S1 via any suitable means, including, but not limited to, welding or an interference fit. In an example embodiment, actuators 150 and 151 are pancake solenoids arranged on either side of plates 146 and 148, respectively, to mechanically actuate assembly 142 and displace assembly 142 in axial directions AD1 and AD2, respectively.

In an example embodiment, wedge plate 106 includes a plurality of apertures, for example, A1, A2, A3, A4, and A5, wedge plate 108 includes a plurality of apertures, for example, B1, B2, B3, B4, and B5, and engagement assembly 142 includes a plurality of shafts, for example, S1, S2, S3, S4 and S5 extending axially through apertures A1, A2, A3, A4, and AS and B1, B2, B3, B4, and B5, respectively. For example, shaft S1 extends axially through apertures A1 and B1 and shaft S2 extends axially through apertures A2 and B2. For a drive mode, wedge plates 106 and 108 are arranged to be rotatable with respect to shafts S1, S2, S3, S4 and S5 so that wedge plates 106 and 108 rotate with respect to hub 104 and non-rotatably connect to rotatable stator 102 and hub 104.

To initiate the advance mode, wedge plate 108 is arranged to be rotatable with respect to shafts S1, S2, S3, S4 and S5 so that wedge plate 108 rotates with respect to hub 104 and non-rotatably connects to rotatable stator 102 and hub 104. To initiate a retard mode, wedge plate 106 is arranged to be rotatable with respect to shafts S1, S2, S3, S4 and S5 so that wedge plate 106 rotates with respect to hub 104 and non-rotatably connects to rotatable stator 102 and hub 104.

Shafts S1, S2, S3, S4 and S5 are circumferentially disposed between plates 146 and 148. In other words, plate 146 is separated from plate 148 axially by shafts S1, S2, S3, S4 and S5. As noted above, engagement assembly 142 is displaceable in axial directions AD1 and AD2 via actuators 150 and 151.

For the advance mode, engagement assembly 142 is displaced in axial direction AD1, shafts S1, S2, S3, S4 and S5 non-rotatably connect with wedge plate 106, wedge plate 106 is disengaged from hub 104, and wedge plate 108 is engageable with hub 104.

For the retard mode, engagement assembly 142 is displaced in axial direction AD2, shafts S1, S2, S3, S4 and S5 are non-rotatably connected with wedge plate 108, wedge plate 106 is disengaged, and wedge plate 108 is engaged and non-rotatably connected to hub 104.

For the drive mode, engagement assembly 142 is displaced in axial direction AD1 or AD2, wedge plates 106 and 108 are disengaged from shafts S1, S2, S3, S4 and S5, and wedge plates 106 and 108 are engageable with hub 104.

The discussion above pertaining to the portions and outer diameters of S1 equally applies to S2, S3, S4 and S5. In other words, each of shafts S2, S3, S4 and S5 are substantially identical to shaft S1. For example, in the drive mode, portions P1 and P2 of each of shafts S1, S2, S3, S4 and S5 are disposed in apertures A1, A2, A3, A4, and A5 and B1, B2, B3, B4, and B5, respectively. In the advance mode: portion P2 of each shaft S1, S2, S3, S4 and S5 is disposed in apertures B1, B2, B3, B4, and B5 and portion P3 of each shaft S1, S2, S3, S4 and S5 is disposed in apertures A1, A2, A3, A4, and A5. In the retard mode: portion P1 of each shaft S1, S2, S3, S4 and S5 is disposed in apertures A1, A2, A3, A4, and A5 and portion P3 of each shaft S1, S2, S3, S4 and S5 is disposed in apertures B1, B2, B3, B4, and B5. In the advance mode, shafts S1, S2, S3, S4 and S5 are arranged to block rotation of wedge plate 106 with respect to hub 104 and in the retard mode, shafts S1, S2, S3, S4 and S5 are arranged to block rotation of wedge plate 108 with respect to hub 104.

The invention is not limited to the arrangement or configuration of shafts S1, S2, S3, S4 and S5 and apertures A1, A2, A3, A4, A5, B1, B2, B3, B4, and B5 as depicted in the figures. For example, additional or fewer shafts and apertures are possible.

The discussion above regarding engagement assembly 142 including plates 146 and 148 is applicable to multiple shafts. For example, in an example embodiment, engagement assembly 142 includes: plate 146 directly connected to respective axial ends of shafts S1, S2, S3, S4 and S5 and plate 148 directly connected to respective axial ends, opposite the respective axial ends, of shafts S1, S2, S3, S4 and S5. In an example embodiment, engagement assembly 142 includes: actuator 150 arranged to displace plate 146 in axial direction AD2 and actuator 151 arranged to displace plate 148 in axial direction AD1.

As noted above, phaser 100 is configured to operate in at least three modes: a drive mode; a phase advance mode; and a phase retard mode. The discussion that follows assumes that stator 102 receives rotational torque in direction CD1. Thus, during operation, stator 102, hub 104 and camshaft CS are always rotating in circumferential direction CD1.

In the advance mode, due to the interaction of hub 104 and wedge plates 106 or 108, rotation of stator 102 in direction CD1 is transmitted to hub 104 and hub 104 and camshaft CS rotate in phase with stator 102, within the context of the torsional forces (explained below) from camshaft CS, as follows. The operation in drive mode can be divided into first and second phases. In the first phase, stator 102, wedge plate 106, and hub 104 are non-rotatably connected to transmit rotation of the stator to the hub and wedge plate 108 is rotatable with respect to stator 102. Thus, rotation and torque is transmitted by wedge plate 106 and not wedge plate 108. In the second phase, stator 102, wedge plate 108, and hub 104 are non-rotatably connected to transmit rotation of the stator to the hub and wedge plate 106 is rotatable with respect to stator 102. Thus, rotation and torque is transmitted by wedge plate 108 and not wedge plate 106.

The non-rotatable engagement of stator 102, wedge plate 106, and hub 104 is due to, for example, ramps 126 sliding up ramps 114 in direction CD2. Since distance 120 increases in direction CD2 and distance 132 decreases in direction CD1, wedge plate 106 is forced radially outward and rotationally locks with stator 102 and hub 104. In particular, ramps 114 and 126 are frictionally and compressively locked and outer portion 106A is frictionally and compressively locked in groove 138.

The non-rotatable engagement of stator 102, wedge plate 108, and hub 104 is due to, for example, ramps 128 sliding up ramps 116 in direction CD1. Since distance 124 increases in direction CD1 and distance 136 decreases in direction CD2, wedge plate 108 is forced radially outward and rotationally locks with stator 102 and hub 104. In particular, ramps 116 and 128 are frictionally and compressively locked and outer portion 108A is frictionally and compressively locked in groove 140.

As is known in the art, torsional forces T1 and T2 are transmitted from camshaft CS, in directions CD1 and CD2, respectively, to hub 104 during operation of phaser 100. The torsional force forces are due to interaction of cam lobes on camshaft CS with various components of a valve train (not shown) of which camshaft CS is a part. Torsional forces T1 and T2 are transmitted in a repeating cycle. Hub 104 continues to rotate in direction CD1 in the current example (stator 104 rotating in direction CD1); however, torsional force T1 causes a relative rotation of hub 104 in direction CD1 with respect to the stator and torsional force T2 causes a relative rotation of hub 104 in direction CD2 with respect to the stator. Transmission of torsional force T1 is associated with the first phase in drive mode and transmission of torsional force T2 is associated with the second phase in drive mode in the present example.

To explain the drive mode, we start with phaser 100 operating in the second phase. That is, stator 102, wedge plate 108, and hub 104 are non-rotatably connected. To initiate the transition from the second phase to the first phase, torsional force T1 is transmitted to hub 104, causing hub 104 to rotate in direction CD1 with respect to stator 102 and wedge plate 108. Since distance 124 decreases in direction CD2 and distance 136 increases in direction CD1, as hub 104 is urged in direction CD1, ramps 128 slide down ramps 116 and the frictional and compressive engagement of stator 102, wedge plate 108, and hub 104 decreases. At the same time, the rotation of hub 104 in direction CD1 causes ramps 126 to slide up ramps 114 in direction CD2 and stator 102, wedge plate 106, and hub 104 begin to engage. The configuration of hub 104 and wedge plates 106 and 108 is determined such that as the non-rotatable connection of stator 102, wedge plate 108, and hub 104 is terminating, the non-rotatable connection of stator 102, wedge plate 106, and hub 104 is being established, providing a smooth and continuous transfer of rotation from stator 102 to hub 104.

To initiate the transition from the first phase to the second phase, torsional force T2 is transmitted to hub 104, causing hub 104 to rotate in direction CD2 with respect to stator 102 and wedge plate 106. Since distance 120 decreases in direction CD1 and distance 132 increases in direction CD2, as hub 104 rotates in direction CD2, ramps 126 slide down ramps 114 and the frictional and compressive engagement of stator 102, wedge plate 106, and hub 104 decreases. At the same time, the rotation of hub 104 in direction CD2 causes ramps 128 to slide up ramps 116 in direction CD1 and stator 102, wedge plate 108, and hub 104 engage. The configuration of hub 104 and wedge plates 106 and 108 is determined such that as the non-rotatable connection of hub 104, plate 106, and stator 102 is terminating, the non-rotatable connection of stator 102, wedge plate 108, and hub 104 is being established, providing a smooth and continuous transfer of rotation from the stator to hub 104.

The following describes the phase advance mode. In the course of cycling between the first and second phases of the drive mode, hub 104 rotates distances 162A and 168A, with respect to the stator, in directions CD1 and CD2, respectively, due to torsional forces T1 and T2, respectively. The configuration, noted above, of hub 104 and wedge plates 106 and 108 results in distances 162A and 168A being nominal or negligible; however, for purposes of illustration, distances 162A and 168A have been exaggerated in FIG. 2A. The following is an example of initiating and executing the phase advance mode. Assume phaser 100 is in the second phase and receives torsional force T1 to initiate the first phase. The non-rotational connection of stator 102, wedge plate 108, and hub 104 begins to loosen as described above. However, before ramps 126 can slide up ramps 114, or before ramps 126 slide up ramps 114 far enough to non-rotatably engage stator 102, wedge plate 106, and hub 104, shafts S1, S2, S3, S4 and S5 are displaced in direction AD1 to non-rotatably connect wedge plate 106 and shafts S1, S2, S3, S4 and S5. Thus, as torsional force T1 displaces hub 104 in direction CD1, ramps 114 and 126 do not engage as required for the first phase and hub 104 is free to rotate distance 162B, in direction CD1, beyond distance 162A. As torsional force T2 is received by hub 104, the second phase of the drive mode is executed as normal.

Thus, for each cycle of the first and second drive mode phases and torsional force forces T1 and T2, while wedge plate 106 is non-rotatably connected to shafts S1, S2, S3, S4 and S5, the relative position of hub 104 with respect to stator 102 shifts in direction CD1 by distance 162B. This process is repeatable via successive cycles of the first and second drive mode phases and torsional force forces T1 and T2 to attain the desired shift of hub 104. To terminate the shifting of hub 104 in direction CD1, shafts S1, S2, S3, S4 and S5 are displaced, after transmission of torsional force T2 and prior to transmission of torsional force T1, in direction AD2 to enable rotation of wedge plate 106 with respect to shafts S1, S2, S3, S4 and S5. Hub 104 still oscillates due to torsional force forces T1 and T2, but within the frame of reference of the oscillations, the rotational position of hub 104 with respect to stator 102 has been shifted.

Each distance 162B in direction CD1 is a result of phaser 100 implementing a full cycle of the first and second phases of the drive mode, or stated otherwise, receipt of a full cycle of torsional force forces T1 and T2. To shift hub 104 in direction CD1 by an amount less than distance 162B, shafts S1, S2, S3, S4 and S5 are displaced in direction AD2 to disengage from wedge plate 106 before the transition from the first phase to the second phase. That is, rotation of wedge plate 106 is enabled during the first phase so that ramps 114 and 126 engage and rotationally lock after shafts S1, S2, S3, S4 and S5 have displaced distance 162A, but prior to hub 104 displacing distance 162B.

The following is an example of initiating and executing the phase retard mode. Assume stator 102 is rotating in direction CD1. Assume phaser 100 is in the first phase and receives torsional force T2 to initiate the second phase. The non-rotational connection of stator 102, wedge plate 106, and hub 104 begins to loosen as described above. However, before ramps 128 can slide up ramps 116, or before ramps 128 slide up ramps 116 far enough to non-rotatably engage stator 102, shafts S1, S2, S3, S4 and S5 are displaced in direction AD2 to non-rotatably connect wedge plate 108 and shafts S1, S2, S3, S4 and S5. Thus, as torsional force T2 displaces hub 104 in direction CD2, ramps 116 and 128 do not engage as required for the second phase and hub 104 is free to rotate distance 168B in direction CD2, beyond distance 168A. As torsional force T1 is received by hub 104, the first phase of the drive mode is executed as normal.

Thus, for each cycle of the first and second drive mode phases and torsional force forces T1 and T2, while wedge plate 108 is non-rotatably connected to shafts S1, S2, S3, S4 and S5, the relative position of hub 104 with respect to stator 102 shifts in direction CD2 by distance 168B. This process is repeatable via successive cycles of the first and second drive mode phases and torsional force forces T1 and T2 to attain the desired shift of hub 104. To terminate the shifting of hub 104 in direction CD2, shafts S1, S2, S3, S4 and S5 are displaced, after transmission of torsional force T1 and prior to transmission of torsional force T2, in direction AD1 to enable rotation of wedge plate 108 with respect to shafts S1, S2, S3, S4 and S5. Hub 104 still oscillates due to torsional force forces T1 and T2, but within the frame of reference of the oscillations, the rotational position of hub 104 with respect to stator 102 has been shifted.

Each distance 168B is a result of phaser 100 implementing a full cycle of the first and second phases of the drive mode, or stated otherwise, receipt of a full cycle of torsional forces T1 and T2. To shift hub 104 in direction CD2 by an amount less than distance 168B, shafts S1, S2, S3, S4 and S5 are displaced in direction AD1 to disengage from wedge plate 108 before the transition from the second phase to the first phase. That is, rotation of wedge plate 108 is enabled during the second phase so that ramps 116 and 128 engage and rotationally lock after hub 104 has displaced distance 168A, but prior to hub 104 displacing distance 168B.

The following describes a method for phasing camshaft 100. Although the method is presented as a sequence of steps for clarity, no order should be inferred from the sequence unless explicitly stated. A first step receives, using a gear non-rotatably connected to a housing, torque from an engine. A second step for an advance mode, displacing a shaft for an engagement assembly, the shaft extending axially through first and second apertures in first and second wedge plates, respectively, in a first axial direction. Engaging a first plurality of circumferentially disposed ramps for a hub, arranged to non-rotatably connect to a camshaft, with a second plurality of circumferentially disposed ramps for the first wedge plate. Blocking rotation of the hub, with respect to the stator in a first circumferential direction. Rotating the hub with respect to the stator in a second circumferential direction, opposite the first circumferential direction. A third step for a retard mode, displacing the shaft for the engagement assembly in a second axial direction, opposite the first axial direction. Engaging a third plurality of circumferentially disposed ramps for the hub engage a fourth plurality of circumferentially disposed ramps for the second wedge plate. Blocking rotation of the hub, with respect to the stator in the second circumferential direction. Rotating the hub with respect to the stator in the first circumferential direction. A fourth step for a drive mode, displacing the shaft for the engagement assembly in the first or second axial direction and blocking rotation of the hub, with respect to the stator in the first and second circumferential directions.

In an example embodiment, the engagement assembly includes a plurality of shafts. In an example embodiment, the single shaft or the plurality of shafts are directly connected to plates which are arranged to be displaced in the axial directions by actuators. In an example embodiment, the actuatable plates are directly connected to axial ends of the single shaft or the plurality of shafts. In an example embodiment, the actuators are pancake solenoids arranged on either side of the plates, respectively, to mechanically actuate and displace the single shaft or the plurality of shafts axially.

It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims. 

What is claimed is:
 1. A camshaft phaser, comprising: a rotatable stator arranged to receive torque from an engine; a hub arranged to non-rotatably connect to a camshaft and including first and second pluralities of circumferentially disposed ramps; a first wedge plate including: a first aperture; and, a third plurality of circumferentially disposed ramps engaged with the first plurality of circumferentially disposed ramps; a second wedge plate including: a second aperture; and, a fourth plurality of circumferentially disposed ramps engaged with the second plurality of circumferentially disposed ramps; and, an engagement assembly including a shaft extending axially through the first and second apertures, wherein: for an advance mode, the shaft is arranged to be displaced in a first axial direction so that the hub is rotatable with respect to the stator in a first circumferential direction; and, for a retard mode, the shaft is arranged to be displaced in a second axial direction, opposite the first axial direction, so that the hub is rotatable with respect to the stator in a second circumferential direction, opposite the first circumferential direction.
 2. The camshaft phaser of claim 1, wherein: for the advance mode, rotation of the hub, with respect to the rotatable stator, in the second circumferential direction is blocked; and, for the retard mode, rotation of the hub, with respect to the rotatable stator, in the first circumferential direction is blocked.
 3. The camshaft phaser of claim 1, wherein: for the advance mode: the first wedge plate is non-rotatably connected to the shaft; and, the second wedge plate is rotatable with respect to the shaft; and, for the retard mode: the second wedge plate is non-rotatably connected to the shaft; and, the first wedge plate is rotatable with respect to the shaft.
 4. The camshaft phaser of claim 1, wherein the shaft includes: a first portion having a first outer diameter; a second portion having a second outer diameter; and, a third portion having a third outer diameter greater than the first and second outer diameters, the third portion disposed: in the first aperture in the advance mode; and, in the second aperture in the retard mode.
 5. The camshaft phaser of claim 4, wherein for a drive mode: the first portion is disposed in the first aperture; the second portion is disposed in the second aperture; and, the first and second apertures are arranged to rotate with respect to the shaft to enable relative rotation between the first and second wedge plates, respectively, and the hub.
 6. The camshaft phaser of claim 5, wherein: to shift from the drive mode to the advance mode: the shaft is arranged to block rotation of the first wedge plate with respect to the hub; and, the second aperture is arranged to rotate with respect to the shaft to enable relative rotation between the second wedge plate and the hub; and, to shift from the drive mode to the retard mode: the shaft is arranged to block rotation of the second wedge plate with respect to the hub; and, the first aperture is arranged to rotate with respect to the shaft to enable relative rotation between the first wedge plate and the hub.
 7. The camshaft phaser of claim 5, wherein: to shift from the drive mode to the advance mode, the second aperture is arranged to rotate, with respect to the shaft, in the second circumferential direction; and, to shift from the drive mode to the retard mode, the first aperture is arranged to rotate, with respect to the shaft, in the first circumferential direction.
 8. The camshaft phaser of claim 1, wherein the engagement assembly includes: a first plate directly connected to a first axial end of the shaft; and, a second plate directly connected to a second axial end, opposite the first axial end, of the shaft.
 9. The camshaft phaser of claim 8, wherein the engagement assembly includes: a first actuator arranged to displace the first plate in the first axial direction; and, a second actuator arranged to displace the second plate in the second axial direction.
 10. The camshaft phaser of claim 1, wherein: the rotatable stator includes a radially inner surface with first and second circumferentially extending grooves; and, radially outermost portions of the first and second wedge plates are: disposed in the first and second grooves, respectively, and; frictionally engaged with the first and second grooves, respectively.
 11. A camshaft phaser, comprising: a rotatable stator arranged to receive torque from an engine; a hub arranged to non-rotatably connect to a camshaft and including first and second pluralities of circumferentially disposed ramps; a first wedge plate including: a first plurality of apertures; and, a third plurality of circumferentially disposed ramps engaged with the first plurality of circumferentially disposed ramps; a second wedge plate including: a second plurality of apertures; and, a fourth plurality of circumferentially disposed ramps engaged with the second plurality of circumferentially disposed ramps; and, an engagement assembly including a plurality of shafts extending axially through the first and second pluralities of apertures, wherein: for a drive mode, the first and second wedge plates are arranged to be rotatable with respect to the plurality of shafts so that the first and second wedge plates rotate with respect to the hub and non-rotatably connect to the rotatable stator and the hub; to initiate an advance mode, the second wedge plate is arranged to be rotatable with respect to the plurality of shafts so that the second wedge plate rotates with respect to the hub and non-rotatably connects to the rotatable stator and the hub; and, to initiate a retard mode, the first wedge plate is arranged to be rotatable with respect to the plurality of shafts so that the first wedge plate rotates with respect to the hub and non-rotatably connects to the rotatable stator and the hub.
 12. The camshaft phaser of claim 11, wherein: in the advance mode, the second wedge plate is non-rotatably connected to the hub in a first circumferential direction; and, in the retard mode, the first wedge plate is non-rotatably connected to the hub in a second circumferential direction, opposite the first circumferential direction.
 13. The camshaft phaser of claim 11, wherein: in the advance mode, the second plurality of apertures are arranged to rotate with respect to the plurality of shafts to enable relative rotation between the second wedge plate and the hub; and, in the retard mode, the first plurality of apertures are arranged to rotate with respect to the plurality of shafts to enable relative rotation between the first wedge plate and the hub.
 14. The camshaft phaser of claim 11, wherein each shaft of the plurality of shafts includes: a first portion having a first outer diameter; a second portion having a second outer diameter; and, a third portion having a third outer diameter greater than the first and second outer diameters.
 15. The camshaft phaser of claim 14, wherein: in the drive mode, the first and second portions are disposed in the first and second pluralities of apertures, respectively; in the advance mode: the first portion of said each shaft is disposed in the first plurality of apertures; and, the third portion of each shaft is disposed in the second plurality of apertures; and, in the retard mode: the second portion of said each shaft is disposed in the second plurality of apertures; and, the third portion of each shaft is disposed in the first plurality of apertures.
 16. The camshaft phaser of claim 11, wherein: in the advance mode, the plurality of shafts is arranged to block rotation of the first wedge plate with respect to the hub; and, in the retard mode, the plurality of shafts is arranged to block rotation of the second wedge plate with respect to the hub.
 17. The camshaft phaser of claim 11, wherein the engagement assembly includes: a first plate directly connected to respective first axial ends of the plurality of shafts; and, a second plate directly connected to respective second axial ends, opposite the respective first axial ends, of the plurality of shafts.
 18. The camshaft phaser of claim 17, wherein the engagement assembly includes: a first actuator arranged to displace the first plate in the first axial direction; and, a second actuator arranged to displace the second plate in the second axial direction.
 19. The camshaft phaser of claim 11, wherein the rotatable stator includes at least one radially inwardly extending protrusion disposed circumferentially between adjacent shafts to limit relative rotation between the hub and the rotatable stator.
 20. A method of phasing a camshaft, comprising the steps of: receiving, using a rotatable stator non-rotatably connected to a housing, torque from an engine; for an advance mode, displacing a shaft for an engagement assembly, the shaft extending axially through first and second apertures in first and second wedge plates, respectively, in a first axial direction so that: a first plurality of circumferentially disposed ramps for a hub, arranged to non-rotatably connect to a camshaft, engage a second plurality of circumferentially disposed ramps for the first wedge plate to block rotation of the hub, with respect to the stator in a first circumferential direction; and, the hub is rotatable with respect to the stator in a second circumferential direction, opposite the first circumferential direction; for a retard mode, displacing the shaft for the engagement assembly in a second axial direction, opposite the first axial direction so that: a third plurality of circumferentially disposed ramps for the hub engage a fourth plurality of circumferentially disposed ramps for the second wedge plate to block rotation of the hub, with respect to the stator in the second circumferential direction; and, the hub is rotatable with respect to the stator in the first circumferential direction; and, for a drive mode, displacing the shaft for the engagement assembly in the first or second axial direction to block rotation of the hub, with respect to the stator in the first and second circumferential directions. 